Fuse plug



Ez.y c. DILLoN FUSE PLUG I FAIL.

INVENTOR. 5. C19/4K1. 55 /u. oN

/7 Trax/vf Y Patented Mar. 28, 1950 UNITED STATES PATENT OFFICE substituted for application Serial No. 600,520,

filed June 20, 1945. January 17, 1947, Serial No. 722,568

2 Claims.

This invention relates to electrical fuse plugs and more particularly to fuse plugs for household lighting xtures and appliances as disclosed in my abandoned prior application, Serial Number 600,520, filed June 20, 1945 and for which this application is a substitute.

It is well known that inconvenience and confusion occur if a fuse blows in a main electrical current supply line. The lights all go out and one must iind his way in the darkness or under match or candle light to the fuse box to renew the fuse.

In the earlier non-polarized lighting systems still in use but with modern portable appliances, there is danger of fire being started from shortcircuits in spite of the ordinary fuse protection.

It is the object of my invention to prevent such inconvenience, confusion and danger of lire when a short-circuit blows a fuse. This is accomplished by providing an individual fuse plug forA each lighting fixture or appliance so that only the shorted appliance will be put out of action. Every appliance or iixture may be provided with a fuse of proper amperage to suit its current consumption and thus lessen the danger from overheated shorted wires.

It is a further object of my invention to provide an individual fuse plug of such compact size as will fit the present standard multiple receptacle and narrow plug.

Another object of this invention is to provide a fuse plug which will withstand the ordinary connecting and disconnecting with a receptacle and plug without affecting the delicate fuse wire.

These objects and other advantageous ends will be described hereinafter with the accompanying drawing in which:

Figure 1 is a wiring diagram of a circuit illustrating the function of my invention when a short circuit occurs,

Figure 2 a top view of a fuse plug made in accordance with my invention,

Figure 3 a front view of Figure 2,

Figure 4 a section taken on line 4-4 of Figure 3,

Figure 5 an enlarged section taken on line 5-5 of Figure 4,

Figure 6 a section taken on line I- of Figure 5,

Figure 7 a fragmentary section taken on line '1 -'I of Figure 5,

Figure 8 a fragmentary section taken on line 8 8 of Figure 5, and

Figure 9 a perspective view of a contact forming a part of my invention.

This application filed zoo-115.5)

Referring to Figure 1 of the drawing, I indicates an appliance shown diagrammatically and electrically connected through by fuse plug 2 to a neutral or ground line 3 and a live line 4. A second appliance diagrammatically shown at 5 is electrically connected to ground line 3 and the second live line 6 of a 3 phase current supply as would occur in a non-polarized lighting system.

A ground pipe illustrated at 'I is electrically connected to the ground line 3 and shown in contact with appliance I at 8. Should a short circuit occur in appliance I, the ground side fuse 9 would usually blow. Should the shorted wires become grounded through the appliance to the pipe l, the live side fuse I0 would blow. Thus fuse protection is provided against shorted appliance accidentally grounded by using a fuse in both sides of a circuit.

When an appliance is plugged into a circuit which is not polarized such as shown at 5, and the fuse plug 2 is not used in the circuit of appliance I, one of the main line fuses I I would blow when a short occurred. Usually the ground line fuse would blow nrst. In a non-polarized circuit the current would then travel between lines 4 and 6 through appliances I and 5 at increased voltage, overloading the entire system and causing damage. With a fuse plug 2 connected to each appliance, such overloading of the circuit would be prevented.

The fuse plug is made in the form of a case I2 having a pair of prongs I3 at one end and a pair of receptacle openings I4 at the other end to receive the prongs of a standard plug.

The case is made in halves identical in shape which t each other and the electrical parts they enclose so as to anchor and securely hold them in place.

The halves may be secured to each other by a rivet I5 or other equivalent means such as an eyelet or screw.

Each prong I3 has a contacting end I6 with a hole I1 therein and an anchoring end I8 bent at right angles. A recess I9 in anchoring end I8 is formed by upsetting the metal and spread- By having wings I as well as endwise strains without shifting and distorting the fuse wire.

Each fuse wire 23 is soldered in recess I9 in prong anchoring end I8 and passes 'through a chamber 24 to a contact anchoring end 25 of a contact 26 Where it is soldered in a recess 2l formed from the anchoring end as shown in Figure 9. A pair of locking notches 28 in the opposite edges oi. each contact anchoring end 25 nt bridges 29 in contact nests 3i] in each half of the case. Each nest follows the general contour of the overall thickness of the anchoring end and has the bridges 29 therein.

Each contact is shaped, as shown in Figure 9,.

to provide a bowed portion 3l for engaging the prongs of a standard plug as indicated in dot and dash lines at 32. This portion 3i is normally disposed in a plane at right angles to the plane of anchoring end v25 and has a .hump 33 formed therein to keep the plug prongs in place in the usual manner. The free end 34' of the bowed portion is curved outward so that a smooth slidu ing` surface rides on the wall 35 ci opening i4 when they bowed portion is compressed.

Nesting the anchoring, end 25 in the manner described prevents itV from shifting and distorting the fuse wire by the, sidewise and endwise strainszof connecting` and disconnecting a standu ard plug.

It will be notedthat byv havingV the anchoring ends of: the contactstand-.the prongs pointing out- Wardly; enables Spacing the fuse Wires a Sunicicnt electrical: distance from the proximity of the'standard plug prongs and within an insulating chamber, without increasing the overall thickness of the case'beyond the size of a stand-- ard` plug.

The receptacle openings I4 have prong guides 3S to guide the prongs of. a standard plug into contacting` position. rihey also serve to prevent sidewise` shifting of the standard plug prongs and the contacts. One side` 31 of the guides is inclinedv to slide the` end.` of a plug prong into proper position. Providing guiding means suchl as; guides 3E only where needed enables hollow-- ing out the remainingportion 3ER-of openings I4 for economical manufacturing;

The hcleforrivet I` isgenlargedat 3B for the rivet'head` and.rv its upset end. The walls around the hole merge intoA thel walls of openings le. Cavities 4i] in the center of the, casefhalt lighten the` case and also facilitate uniform curing the plastic material` from which the case may be made.

Communicating passages 4I in the four walls between fuse chambers 2liV permit escape of air when either orboth fuses 23: blow. The passages 4I, permit escape of gases into cavities il and contact openings 33 whereby the cubic capacity offfuse chambersf24 will be increased thus serving to prevent exploding the casewhen an unusually good sealing iit is made by the case halves around chambers 24.

The contact openings I4 when in use are substantially .sealed by contacts 26, the prongs on the plug, andthe guides` 36.

When only one fuse blows, the pressure is further released without` damage to casing by connection straightv through into the other fuse chamber.

'Ioinsure proper matching of the nests, chain" bers, openingsand cavities of one case half with theother when they are assembled and thereby further insurelining up the prongs and contacts,

L provide adoWel-lug 42 at diagonally opposite corners of each case half. When the case halves are assembled, the dowel lugs of one case half will nt the open corners of the other case half. Thus one case half is properly lined up with the other case half and both halves are locked to each other at their four corners against turning around the rivet I5. By having the nests Zi and 30 properly aligned, the prongs i3 and contacts 2E iitting these nests will also be correctly aligned. Displacement of the case halves by abnormal strains on a prong I3 is thus prevented by the locking fit of dowels 42.

To assemble the fuse plug 2, first a prong I3 and contact. 26 is held in a suitable xture in the same relation as they would be held in their nests 2I and 30 respectively. Then a fuse wire 23' is placed on. the prong and contact and the ruse ends bent into the recesses and soldered therein. Two such assemblies of the prongs, contacts and fuses are then placed in one half of` the case. The other case half is placed over the. prongs` and contacts and brought against therst case half with-:dowels 42 fitting the open corners. The case' halves are then secured to each otherby rivet I5. The fuse plug is now ready for use.

It is thus seen that by arranging the prongs and contacts with their contacting sides paral lel to. each. other in the `direction of the thickness of the case, it was` possible` tofmake a case half having nests parallel to eachother in the direction of their depth. Thus providing` a case half which maybe easily moulded'Y from plastic material and readily slipped over the contacts and prongs to securely hold themin assembled position.

In use the fuseplug is connected to a fixture or appliance by inserting its standard plug prongsinto opening I 4. During this action bowed portion 3| of each contact will be compressed by the plug prong and hump 33 will snap'into the prong opening. The; fuse plug is then inserted into a standard receptacle in the same manner asa standard plug, is inserted. The appliance or fixtureis now ready for use with fuse protection as described above.

Should the appliance wiring become snorted, the groundside fuse i! as indicated inl Figure 1 would ordinarily blow. If the appliance happened to be in contact with a grounded object like a water pipe, radiator'or bath tub, and the shorted Wire was accidentally grounded to the appliance, then` the other live wire fuse I0 would blow, thusaffording full fuse protection to both sides of an electric supply line at each appliance.

It will be noted that by making the prongs and contacts with their anchoring ends bent outwardly from thefcenter oi4 the fuse plug, suf cient space is provided in the-casefior. the fuse wire, Without increasing the thicknessorthe case beyond the sizeof a standard plug, thus enabling the fuse plug to be used'k in the present closely spaced multiple receptacles.

It'should also beinoted'that amaximum fuse length may be obtained in a minimum case length with an` arrangement of prongs and contacts having anchoring ends nested at an angleito'their electrical contacting ends.'

While I have set forth my invention in a particular form, itwill be understood, that its shape may be changed.withoutaifecting the. function thereof, and hence I do not limitmyself to the precise constructionset forth, but consider it `my f liberty to make such changesiand. alterationsas.

s fairly come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent ist l. A fuse plug comprising a casing having a pair of parallel openings substantially the full depth of the case, a pair oi fuse wire chambers at the outer side of said openings and of substantially the same length as said openings, said openings and said chambers being substantially in alignment crosswise of said casing, a contact nest communicating with the outer end oi each opening and one end of the adjacent chamber,

each nest having bridges therein, a prong nest communicating with the other end of each chamber and extending inwardly toward, then outwardly in line with, the parallel openings; a pair of prongs having anchoring ends tting securely one in each of the prong nests, each anchoring end being wider than the prong and having a recess in said wide portion; a pair of contacts one in each of the openings each being formed. to provide a recess in its anchoring end and a pair of locking notches at each side of the recess fitting said bridges in the contact nests to prevent shifting; and a iuse wire in each chamber soldered to the contact and prong recesses, said contact and prong ends with the fuse wire soldered thereto substantially filling the respective nests to seal them to prevent escape of heated gas and fuse material from the chambers.

2. A fused attachment plug, comprising a rectangular casing of insulating material having identically formed opposing side portions and being greater in width than in length, and greater in length than in thickness when the inner surfaces of the opposing side portions are in abutting relation, said casing portions having relatively thin top and bottom walls, front and rear walls, and side walls, means to tightly secure the casing portions together, each of said side portions having a central wall extending lengthwise, from the front wall to substantially the rear wall, a contact opening in each of the side portions along each side of the central wall, a crosswise wall spaced forwardly from the rear wall to close the inner end of each contact opening, and an opening through the front wall connecting with each contact opening, a fuse member chamber alongside of each top and bottom wall and extending lengthwise of the casing portion from the front wall to the rear wall and parallel to the adjacent lengthwise contact opening, a lengthwise wall between each chamber and the adjacent contact opening, said crosswise wall extending between the rear end oi said lengthwise wall and said central wall, each chamber extending from the iront end of the adjacent lengthwise opening to beyond the wall at the closed inner end of each contact opening and from the inner surface of the side portion laterally to the adjacent side wall thereof, prong openings through the rear wall, one on each side of the central wall, a rst passageway between the rear wall and the wall at the closed end of each lengthwise contact opening to connect the prong opening with the adjacent chamber' at its rear end, a second passageway extending alongside the iront wall to connect each of the lengthwise Contact openings with the front end oi the adjacent chamber, all of the passageways being disposed at right angles to the lengthwise contact openings and the fuse members chambers, a metallic prong disposed in each prong opening and having a blade portion extending from the casing beyond the rear wall thereof, said prong having a terminal end portion bent at right angles to the blade portion, disposed in the first passageway to substantially the lengthwise center of the chamber, a metallic contact member disposed in each contact opening and having an end portion bent at right angles thereto and disposed in the second passageway, said contact member end portion eX- tending into the front end of the adjacent chamber alongside the casing iront wall to substantially the lengthwise center of the chamber, and with its outer end substantially in lengthwise alignment with the outer end oi the prong end portion, and a length of fusible material in each chamber extending between and electrically connected to the prong end and the contact end in each chamber, said length o1" fusible material being substantially parallel to the meeting surfaces of the casing portions intermediate the side walls of said portions.

BERNARD CHARLES DILLON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,749,364 Weisberg Mar. 4, 1930 1,819,910 Mattia Aug. 18, 1931 1,850,672 Heller Mar. 22, 1932 1,892,567 Craddock Dec. 27, 1932 1,990,176 Fried Feb. 5, 1935 2,013,596 Becker Sept. 3, 1935 

